Selecting network



Aug- 10, 1954 J. P. ECKERT, JR

SELECTING NETWORK 6 Sheets-Sheet l Filed June 24 1950 INVENTOR.

Aug. l0, 1954 J. P. ECKERT, JR 2,686,299

SELECTING NETWORK Filed June 24, 1950 v 6 Shee'cs-Shee\`l 2 ug 10 l954 J. P. ECKERT, JR 2,686,299

SELECTING NETWORK Filed J une 24, 1950 5 sheetsheet 3 IN V EN TOR.

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Filed June 24, 1950 J. P. ECKERT, JR

SELECTING NETWORK 6 Sheets-Sheet 4 INVENTOR.

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Allg. 10, 1954 J, P ECKERT, JR 2,686,299

SELECTING NETWORK Filed June 24, 1950 6 Shegts-Sheet 5 6 Sheets-Sheet 6 Filed June 24, 1950 www www

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kwik ww Patented Aug. l0, 1954 anni SELECTIN G NETVV'ORK John Prosper Eckert, Jr., Philadelphia, Pa., as-

signer, by mesne assignments, to Remington Rand Inc., New York, N. Y., a corporation of Delaware Application .lune 24, 1950, Serial No. 170,215

1 12 Claims.

This invention relates to selecting networks, and more particularly to networks of this type making use ci the properties of unilateral conduetors.

There are inany applications in which it is desired to eacute unique combinations of operations whenever a predetermined set ci stimuli occurs. `i/'here considerable amounts oi power are available and the time for setting up and carrying out any of the predetermined sequences is relatively long, relay coils actuating sets of contacts may be used for this purpose. When the number of choices is relatively small and the speeds or" operation required are of the order of a few hundred per second, it is possible to employ resistance .matrces for networks to carry out the desired selecting operation. When the ultimate in speed, by todays standards, is required it has been found that the unilateral conducting properties of germanium crystal diodes and the like connected into selecting matrices may oe employed with material advantage. T Ae use ci such unilateral conductors, however, because of their special properties, requires consideration of several aspects of circuit performance which are not Lediately obvious, but which Will be discussed below.

One of the objects of the invention is to provide a new and novel selecting network particularly adapted for high speed operation.

Another object of the invention is to provide a new and novel selecting network adapted for actuation from pairs of alternatively operative electric valves.

A .further object of the invention is to provide a new and novel selecting network delivering norsignals to the associated control channels.

Still another object of the invention is to provide a new and improved apparatus for developing arbitrary output stimuli combinations in response to equally arbitrary input stimuli combinations.

Yet a further object of the invention is to proa new and improved network for the energization of circuits through unilateral conductors reducing the undesirable efects oi back resistance.

Other objects and advantages of the invention w. l in part be described and in part be obvious when the following specication is read in cot notion with drawings in which:

Figure 1 illustrates schematically a selecting network driven from a storage register including electric valves,

Figure 2 illustrates schematically a selecting network combining the indications of banks of ves to select unique elements,

3 illustrates schematically a selective storage register of somewhat greater` nan is illustratedv in Figure l,

n etwel; capacity t Figure 4 illustrates schematically a selecting network actuated from a counter chain,

Figure 5 illustrates in schematic form apparatus combining the selectin#Jr action oi the apparatus of F'igu es l, 3, and in conjunction with an additional selectinglnetwork, and

Figure 6 illustrates in schematic form a selecting network converting single line indications into multiple channel stimuli.

The schematic diagram of Figure l illustl ates the cooperation oi a number of nip-flops with a selecting network incorporating diodes for separately exciting output conductors, one at a time, depending upon the combinations set up in the flip-nop register.

One of the coupling valve and iiip -flop arrangements will be described in detail, it being understood that the balance of the circuits are essentially the same and function in substantially the same manner. A flip-liep 2li is excited from the coupling valve 2i having a control electrode 22 connected, through capacitor 23, with a point on the transmission line 24. The line 2t may coinprise any ofthe conventional transmission line structures, and is here illustrated as made up of a series or sections including series inductance and parallel capacitance and is terminated in its characteristic impedance For convenient reference, all supply buses will be identified with a number corresponding with their voltage, even numbers being employed for positive voltages and odd numbers for negative voltages. In addition, the control electrode 22 may be returned to a negative supply bus l! through a resistor 25,`

which is shunted by diodes 25 so poled as to prevent the development of negative-going surges across the resistor 25. The valve 2i is further provided with a cathode 2l returned to ground and an anode 2li connected with a positive supply bus lll through resistor 29. A space charge grid 33 is connected. with a positive supply bus EG, while the inner control electrode i! is connected with a setup signal input terminal through capacitor 33 to a negative supply bus l through the resistor 34.

Signals appearing across the resistor load 2% are impressed on the control grid i2 of the iiipliop 3 through a capacitor l l, whose grid end is returned to the supply bus l! through resistor rlhe valve i3 may be of the type commercially designated AS5 and is further provided with an anode lll returned to ground through load resistor l5 and a cathode ifi connected with the supply bus lill.

Flip-flop 2li also includes a valve fl'i having an anode 43 connected with ground through the resistor 55% and a cathode il? returned to the negative supply bus lili. A resistance-capacitance network 5i connects the auxiliary control electrode 52 oi the valve Il?, with the anode 43 of the valve 4l, While the auxiliary control electrode 3E of the yvalve 6l yis.connected'through the resistance-capacitance network ajfwith the anode il of the valve |53. Space charge grids 5t, 55 are connected with the negative supply bus di and the inner control electrode 40 of the valve 1i is connected to the clearing bus 56, which'v is returned through a resistor 51 to the negativesup-v The `selecting.network isznot'actuated directly from the nip-nop 2t, but rather'through the intermediate functiontable driver valves.v S2 and 63.- The control grid Slt-:of the-valve E2 is connected through :resistance -66to the anode M of the flip-flop valve 63, while its anode ES is connected.: through the load resistorft with the positive-supply busY 20: Unilateral conductors, which may be germanium crystal diodes for high speed-operation, or, for lower speed operati-on, the well-known: copper oxide, selenium. or magnesium sulfide types, are connected lbetween the anode tand the linesleifand- IBZ-at I03and 05 with the 'polarityjndicated A unilateral conductor l2, poledl to limit negative excursions of the anode 68,.is Vconnected,betweenthe saidanode S3 and thernegative supplybus Il; Asimilar unilateral conductor 14.. may be connected betvveenY the anode 680ithevalve V(i2 and ground in series with`.the-resistor 16,' poledto limit positive excursions. The space charge'grid 'i3 of the valve 62fmay-also Ice-connected with ground, while the'cathode 853 .is returned to thenegative supply bus-6I.

Similar connectionsl link vthe control electrode 651-of`valve `53 -with the anode 480i-the nip-nop valve =4| via the resistorfl;l Thespace charge grid v|53 ofxvalve Slis similarly connected -with ground, while its anode 69 is connected with the positive supply bus I20`throughload resistor '|I and-joined tothe conducting lines |04, |06, by unilateral conductors atl |01 and IML-connected With they polarityindicated. In addition; the anode-'6B is connectedthrough'the negative excursion limiting diode 13 -With the negative sup-V ply vbus Ii and with ground through the positive excursion limiting diode 'l5 inv series with the resistor 'VL The-'cathode 8| iisconnected with the negative supply bus* 6 I The'lines |00, m2;l |54 and |06v are respectively connectedy through represented'generally by theV load `resistors 95, gli, andes returned'to` the'negative supply usV A further coupling valve A`Sii-'is :connected with the flip-nop 82 comprising the'fvalves 8B and 8i' situated in circuitsfwhich may be identical with those previously described. A function table driver rvalve 84'is coupledltothe-anode circuit of the flip-oprvalve 85and the anode 30 of the valve 84 is connected With the load impedance I 0 and conducting lines |00 and |04 by unilateral conductors at III and II2, poledv as indicated. A similar function table driver valve05 is connected to the anode circuit of the Valve 81- of nip-flop 82, the anode 8g of the valve85 `being connected with:the .load impedance II3 and withv the conductinglines |92 and |05 through unilateral conductors, poled as shown, at II I4 "and I I5.

The rauxiliary-control grid lof Ithevalve 8.3 is coupled Withrthe transmission lineJ tap 9|; and.

intermediate circuits i.

theinner control grid of thefcoupling valve 83 is linked to capacitor 33 and thence-to the setup signal terminal 32. The clearing bus 56 is connected with the inner control eelctrode of the valve Si in the flip-flop 82. Y

The reference states of the valves making up the apparatus oi Figure 1 are as illustrated, the shaded valves-being conducting. When it is desired to place'. this vequipment in operation, the existence of the lreference state is insured by actuation of the momentary switch 58 which disconnects the capacitor 59 from the negative supply `bus 19| :and connects it with the clearing line to impress a cutoff Voltage on the inner control electrodesof valve iii in the flip-nopl Eiland the valve Si in the flip-flop S2. The interruptionof current iioW through the Valve develops a positive-going voltage at the anode 33, which is coupled through the resistance-capacitance network 5Iy to .the auxiliary control electrode 52 ofthe -valve permitting` the flow of current to the anode @it to reduce vits potential and thereby impress a relatively negative voltage through the resistancewapacitance network 53 on .they auX- iliarycontrol electrode of the valve l, which maintains the valves? nonconductive, While constantially-the same manner. When these circuit` conditionsl prevail, the function table driver valves 22 and Sil, Whose control electrodesare linked with: the anode circuit-o the conductive side of flip-flops 2G and lii'Z respectively, are rendered nonconductive, While the function table driver valves S3 and ihaving their control. electrodes linked with the anode circuits of the non-y conductiveside of the flip-flops 20 and 82, respec-A tively, are conductive.

Thev clamping action of the negative excursion limiting diodes restraint ancdes 55.3 and @t at minus-seventeen volts which, it Wiil he` noted, makes the cathodes of the diodes it?, 553i), I it, and I I negative With respect toY their associated anodes, producing a flow or current therethrough shifting thepotentials of lines iii?, Et, and IGS.-

to avalue of approximately, minus l? volts.

The absence of conduction in the anodes ci functiontable driver valvesii and Sii permits the associated anodes Sii and iito rise to a potential somewhat more positivev than ground due tothe Clamping action of the positive excursion limiting diode 'It in series with the resistor 'H3 in the anode circuit of thevalve E2 and its counterpart'in the yanodecircuit of valve t. The'lines F associated with the loads i0, and Illgv therefore become positive; This makes the potential of the cathode 0I" the unilateral conductor indicated at |05 more positive, butthis eiiectively disconnects the unilateral conductor at I05-froxn across line' |02 because conduction at Hsin' the anode circ-uit of the valve vniakes the crossv line |01?.`

negative. Lines |04. and |06 are already maintainednegative by virtue of the diodeconduction Qccurring at Illland |09 inthe anode -circuit ci ya1ve63. However, since-thevalves 52.

and 84 are nonconductive, making the cathodes of the diodes at 63 and li l more positive, the diode end of the load e5 is free to also become positive with respect to the cross lines H32, itil, and itt. this arrangement of conluctors and diodes may be regarded as a function table having the property of exciting the cross line lo@ .vhenever the valves t2 and are nonconductive, while maintaining the cross lines H32, lill, and it biased to an inoperative potential.

In the specific example being employed for illustrative purposes, it may be next assumed that a time sequence of intelligence-bearing impulses is impressed on the input of the transmission line 24 and propagated therealong, to be absorbed in the terminating load S2. For convenience it is assumed that the intelligence considered exists in the .form of pulse groups spaced in time. As ive have shovn a delay line 2li with the taps 3S and Si spaced by a single pulse time, it may be considered, in this simple illustration, that only two pulses are located within a given group. At the time when the leading pulse in the group would arrive7 if present, at the delay line tap el, a positive-going setup signal having a duration of one pulse or less is impressed on the terminal 3?., conditioning the coupling valves 2l and S3 for the passage of a signal to the associated flip-flop, if there is coincident excitation of the corresponding tap on the delay line at this instant. The coupling valves El and 13 therefore act as gates, with the inner ectrode receiving conditioning or alerting signal.

in the assumed case, an anode current surge is developed in the gating valve resulting in the impression of a negative-going signal on control grid ft2 oi the flip-flop valve interrupting con-duction through valve to develop at its anode lil a positive-going stimulus applied to the auxiliary control grid 353 through the coupling network 53, which initia es conduction through this valve. This conduction reduces the potential at the anode il@ of the valve il?, to impress upon the auxiliary control grid 52 of the valve CL3 through the coupling network iii, a negative signal maintaining the valve in the off condition.

Since no signal appears at the transmission line terminal el during the alerting interval, the valve 53 en ains inoperative and the flip-nop its reference state.

i he -lop in its abnormal state, the function le driver valve is biased to cutoff by virtue of the potential drop occurring in the anode resistor uit, to Ywhich it is connected through a resistor 5l, While no such drop occurs in the anode resistor d5, pitting conduction through the function table driver valve G2. Simiconduction continues through the function table driver valve Se because of the relatively positive potential applied to its control grid. rThe conduction through the function table driver valve Si? reduces the potential of the anode and the associated conductor connecting it with the load 'lil to about seventeen volts negative with respect to ground, causing conduction through the unilateral conductors 33 and li holding the lines lili? and at the minus seventeen volt level. The conduction through the valve t5 holds the cross lines its and leal at substantially the same potentials for the same reasons. This leaves the line unaffected by the conduction of the valves 52 and 85. The cross line ille is connected through diodes at itl and H2 With the anodes t9 and 88 of nonconducting H Figure l through valves 63 and 84 which, by reason of their nonconduction, elevate the potential oi the cathodes of the associated diodes positively, permitting the line It to assume ground potential through the resistor 97.

Other combinations of the reference and abnormal states in the flip-flops 2e and t2 will result in selection of other conductors from the group lilo, 102, m4, and Hill in a manner which may be readily derived in the light of the foregoing explanation.

The flip-flops 20 and 82 may be regarded as a register for the storage of information originally present in the form of a serial pulse train. They are often referred to as a static register because this information remains present in the .flip-flops until they have been deliberately reset. The network of conductors and diodes ffii-i i5 has referred to as a function table, this terni being chosen because of its property of uniquely selecting a single conductor as a function of `the various input combinations which may be ezcited.

A function table such as that istrated in Figure l, which uniquely selects a single line in response to diiering input combina ns, may be conveniently referred to as a decoding function table, while function tables performing the inverse function of exciting groups of output conductors in response to the excitation or" a single line may be conveniently referred to as. an encoding function table.

The function table described in Figw a type providing a positive-going i tion on `the selected line. Other function tables c eveloping negative-going impulses on the 3 output lines are illustrated in Figure 2 which further develops the combined use of a plurality or function tables in performing a final selecting operation. he tables shown in Figure 2 select on the basis of of combinations of conducting valves, while the table illustrated in Figure l performs its selection on the basis of combinations of nonconductiog valves. The arrangement of I ure 2 bank U25, of function table drivers including the valves 12E-428, whose anodes are connected respectively with the vertical lines itl-J which are excited from the positive supply bus through the loads 2S-E36 respectively. The cathodes of the function table driver valves in the bant: i may be returned to the negative supply bus iii, while their space charge electrodes are connected with ground. The control electrodes of these valves may be connected with a flip-liep static regista of the type illustrated in circuits similar to those there describe-tl. The cross-connecting or horizontal lines 15G-59 are connected with the vertical lines itil-HM through unilateral conductors with the indicated sense at the points marked. connections are made in accordance '..vitlf following table:

Driver Lines Input Line l The output lines i5@ through are individually nected with the negative supply bus At their other extremity the outputlines ld through 59 connect individually with control electrode-s of valves 25e, 22y 222, 22S, 252, 22E, 225?, 253, and 2de respectively, which have their cathodes returned to ground and their space charge elec- -rcdes connected with the positivesupply bus d. The valves 25d-262, inclusive, may be triodes or may be multiple grid valves, as illustrated. It will be noted that the unilateral conductor or diode connections correspond to the binary designation of the decimal numerals in an excess-three cede, which is to say that the binary numbers expressed thereby are quantitatively equal yto the decimal quantity to be expressed plus three.

Th operation of the function table driven from the valve bank 25 is as follows: Each ci the following groups of valves constitutes a pair, characterized by alternative conduction thrcugi` one or the other of the pair members, in accordance with the setting of the flip-liep static register previously described; 2, 22; 23, E22; 25, 26; and i2?, (22. Any set of conductive conditions satisfying the above limitations may be used as a reference state. lt is assumed new that the flip-flop static register governing the valve barils 25 has been set up to produce the conduction pattern illustrated in Figure 2. The following valves are conductive: i2 i, 22, 23. This corresponds to the number 6101 in binary form which is expressed in the more familiar decimal notation as 5 but, since we are employing an excess-three code, representing the tru decimal number The selective negative en ization of the cross line E52 takes piace as folio s: Conduction ythrough the valve 2 reduces the potential on the line 37 to a relatively low value, somewhat negative with respect to ground, creating the possibility .that one of conductors iti), lei, 52, 53, or i5@ may assume a negative pctential. The valve 22 is nonconductive, whereby the conductor 38 is positive with respect to ground, 'producing conduction through the diodes its, itl', 35?, its, and ile, thereby maintaining the lines E52, 52, E58, and 59 positive with respect to ground and causing the valves 25?, 22S, and 252 i c remain conductive, even though others or the ver 'cal conductors may be negative with respect to ground. This is true be cause the application of a negative potential to the anode of any diode already associated with one oi the positive lines just recited. is eifective merely to disconnect the diode presenting only reverse impedance to the circuit. Hence, it will not be necessary to further consider diodes connected to the lines ii-i 59.

The valve 23 is likewise nonconductive, Whereby conduction occurs through the diode connected with the line |52, preventing this line from swinging negative. Next in order is the valve 22 which is conductive and the resulting negative potential on the line ist connected with the load 32 develops negative potential across the diodes 80, 8I, 82, and 83 which will not interfere with the negative excursion of any one of the lines l5, 52, 53, 52. Likewise, the valve 25 is conductive to reduce the potential on the vertical line IM, applying a negative potential to the diodes at E25 and 86, so that there is no interference at either of these points with the lines 55 or 52 assuming a negative potential. The lack of conduction through the valve 25 results in an elevation of the potential of the vertical line 22, producing conduction at the diodes 22, 93, and 94l preventing their associated lines l, 53, and

8 ld from becoming negative. Likewise, the valve 21 is nonconductive so that the positive potential resulting at the line i553 initiates conduction through the diodes lei, 98 eliminating the lines 5 and 53 as possible negative conductors. The valve 122 is conductive, making the vertical line 144 negative whereby conduction is prevented through the diodes 222, 2%3, and 282.

A review of the conditions prevailing in the diode-conductor network illustrates that the line 50 is prevented by conduction through the diodes at iii, 52 from becoming negative. The line 5 is prevented by conduction through the diode at 91 from becoming negative. The line 53 is prevented by conduction through the diodes at 93 and 98 from becoming negative; the line 52 is prevented by conduction through the diode at i from becoming negative. Only the line 52 is connected through diodes at 22, Il, it, and 203 with vertical lines having relatively negative potentials, whereby all the said diodes are effectively disconnected from the line 52, except for their reverse resistance, whereby the line is free to assume a potential of minus l1 volts through its associated individual load impedance. The line 52, distinguished on the diagram by its heavier appearance, upon becoming negative, interrupts the flow of current through the valve 262, developing a positive-going excursion in its anode circuit and the conductor connections associated therewith.

Completion of the selection is obtained through the use of a second function table driven from the Valve bank 22, consisting of valves driving the vertical conductors 2id, 2l, 2id, 2id, 2l?, 28, EIS, and 22B which are returned to the positive supply bus |29 through a bank of individual compensated load impedances 2 I El. A number of unilateral conductors connected at the piaces indicated with the polarity shown connect the vertical or input lines with the horizontal or output conductors 225, 23|, 232, 233, 232, 235, 23S, 231, 238, and 23S returned through individual members of the impedance bank 252 to a potential of minus l1 volts.

Selection of one of the horizontal conductors in accordance with the pattern of conduction and nonconduction in the valve bank 2 i2 is performed in the same manner as was developed in connection with the previous function table driven from the valve bank 25. The conduction pattern in the bank 2 l2 is illustrated as setting up the binary number i061, which is edith/aient to the decimal number 9, or, bearing in mind that th-e excessthree code has been employed, 6. rIhe heavy line conductor 236 is therefore permitted to swing negatively.

It will be noted that the conductors 235)-239 are coupled in pairs to the control elements of the valves and irough the individual diodes 26E- 229, poled to pass negative-going impulses. Negative excursion of the line 235 initiates conduction in the diode 245, placing a negative potential on the control electrode of valve 25@ to interrupt the now of anode current therethrough, causing a positive voltage excursion in the anode circuit and conductors associated therewith. This line is accented in Figure 2.

The various connections shown emanating from the anode lines associated with the valves 260-269 and 256, 252, 25d, and 253 are connected in pairs to coincidence selecting circuits of the same or other types where a gating function may be performed .on any desired circuit.

Preparatory to the showing and discussion of a more complex switching and selecting organization, such as might be employed in connection with a high speed electronic computer, the organization of Figure 3, illustrating a three-stage static register, similar in its construction and properties to the register of Figure 1 has been illustrated. A coupling gate 304 is connected with the junction 30| on a two-section transmission line 324, and the output of the gating valve 344 may be connected with one side of the nip-flop 335.

Another coupling gtte 365 has its auxiliary control electrode connected with the junction point 302 on the transmission line 324 and its output connected with the left-hand side of the nip-nop 301. A third coupling valve 338 also has its auxiliary control electrode connected with the junction 303 on the transmission line 324, and its output is delivered to the lett-hand side of the iiipiiop 309.

rihe inner grids of the coupling gates 344, 335, and 308 are connected together and, through the capacitor 33, to the setup signal input terminal 32, which is excited by a stimulus related to the signals applied to the transmission line 324 in a fashion sirnilar to that already described in connection with Figure l. The auxiliary control grids of the flip-flops 335, 332', and 309 are connected through appropriate impedances with the negative supply bus 13|. The inner control grids of the right-hand valves of the nip-flops 335, 3D1, and 303 are connected together and to the clearing bus 355 returned to the cathode supply bus through resistor 351 and connected with one pole of the single-pole double-throw switch 258, Whose other pole is connected with the negative supply bus i 9 While the movable contact is returned to ground through capacitor 359. The flip-flop 305 excites the function table driver valves 324 and 32|, while the flip-nop 301 excites the function ral-*le driver valves and While flip-nop 38.5 excites corresponding function table driver valves 324 and 325. When this assembly is in its reference state, the left-hand sides of the flipfiops 305, 301, 309 are conducting, as are the valves 32 I, 323, and 325.

The driver valve 320 is connected via the line 340 and resistor 330 to the positive supply bus |20. In addition, the valves 32|, 322, 323, 324, 325, respectively, are connected over the lines 34|, 342, 343, 344, and 345, respectively, With the positive supply bus |20 through resistors 33|, 332, 333, 334, and 335 respectively. Unilateral conductors are connected at the points and in the senses shown, whereby unique combinations of i conducting valves select one of the output conductors 330, 33|, 332, 353, 354, 355, 35E, or 361. The operation of this register and associated function table is so similar to the operation of the apparatus in Figure 1 as to preclude the necessity of a detailed repetition of the operating details at this point.

Suflice it to say that the combination permits the selection of one output conductor for each unique combination of the distribution of the states of conductivity and nonconductivity in the register.

The foregoing function tables of Figures 1 and 3 together with their associated driving equipment have been characterized by perfect symmetry. The arrangement of Figure 4 illustrates a counter chain driving a function table network, in which the alternatively conductive members of the counter stages, whose internal structure is much like that of the nip-flops previously de- I0 scribed, excite an array of valves connected with the input lines of the function table.

Negative-going counter driving impulses are impressed on the input terminal 423 and applied through capacitor 4|9 to the control grid of the coupling valve 4|6 having the resistor 4&3 in its cathode circuit. The control grid is returned to the negative bus 4| through the resistor 421 and the cathode 4|1 is connected with the negative supply bus |3| through the said resistor 4 i 3, making the valve 4|3 normally conductive.

Each counter stage employed may, as in the case illustrated for the stage 399, consist of a dual triode assembly Within a common envelope 400. The cathodes 43E and 4t2 are returned to the negative supply bus |4| and the control grid 403 of the left-hand triode is connected through the resistance-capacitance network 403 to the anode 433 of the right-hand valve, in addition to being connected with the cathode of the diode 422, and through the resistor 4H to the negative supply bus Il. Similarly, the control grid 424 of the right-hand valve section is linked through the resistance-capacitance network 403 with the anode 455 of the left-hand valve assembly. In addition, the anode 435 may be connected with ground through a load resistance 4I5 and the anode 405 may be connected with ground through the load resistance 4|4. A diode 4|3 has its anode connected with the anode 405 and cathode connected with the cathode 4|1 of the input valve 4| e. The anode 403 is similarly connected through a diode 4 i2 with the cathode 4|1. The anode of the diode 422 is connected with the clearing bus 423, which is supplied with positive-going impulses to establish the desired reference pattern of conduction in the array of counter elements. The remaining stages of the counter are indicated at 424, 425, 425, 421, and 428 with the sides conducting in the reference state shaded. These units are similarly connected with the clearing bus 423 by diodes which form a part of their internal structure and are interconnected by driving lines exciting the counterpart of the valve 4 l 6 within the individual assemblies.

The function table input conductors 440, 44|, 442, 443, 444, 445, 446, 441, and 448 are excited from a series of driver valves 434, 43|, 432, 433, 434, 435, 43B, 431, and 438. Each of the function table driver valves is returned to the positive bus 33 through an individual load resistor and is provided \vith clamping diodes arranged in the manner described in connection with Figures 1 and 3. The counter stage 339 governs conduction in driver valves 43) and 43| through the connection of their respective control electrodes with the anodes 405 and 406. In like manner, the nip-nop 424 governs conduction in the coupling valves 432 and 433, while the ilip-fiops 425, 423, and 421 respectively govern the valves 434, 435, and 436. The last stage 428 in the counter chain also controls two driver valves 431 and 433.

r"he vertical line 440 is connected with the lines 464, 45|, and 433 through the diodes 49%, 492, and 493, and vertical line 44| is linked to the horizontal line 452 by diode 494. l'n addition, the diodes 481, 488, and 439 connect the horizontal lines 460, 482, and 463, with the lines 442 and the diode 466 connects the vertical line 443 with the horizontal line 46|. Each of the vertical lines 444, 445, 440 is connected to all the horizontal lines 450, 46|, 462, and 453 through one of the diodes in the group 414-485. Vertical line 441 is linked with the horizontal line 460 by the diode 413 and the vertical line 443 is connected 1i with horizontal lines 05|, 462, and Q53 through the diodes M0, fill, and i512.

The resetting circuit includes the valves 095, 507 and is excited with positive-going impulses through an input capacitor 495 coupled with the cathode 096 of the diode connected triode assembly having electrodes 091. A resistor 508 connects the diode-anode electrode `group 021 with the negative supply bus Ml and a capacitor |98 connects this point with the negative supply bus i9 l. lThe cathode 596 is also returned to this supply bus through the resistor 494. The potentials impressed on the left-hand electrode assembly make this section of the valve i395 normally conductive. However, the clearing impulses periodically applied through the capacitor 099 charge the capacitor G93 with a polarity tending to diminish or cut oif said conduction. The control grid 50| of the right-hand'section of the valve 555 is connected with the grid-anode i9? and the anode 502 of the right-hand section of valve 555 is connected through the resistor 503 with the negative supply bus l0! and to the control electrode 500 of the normally conductive clearing valve 507 which has its anode connected to the negative supply bus 6| and its cathode connected through the resistor 500 with the negative supply bus iti. The cathode 500 of the right-hand section of the valve 095 is also connected to this negative supply bus I9 l. assembly 500, 50|, 502 and the valve 50'! are normally conductive.

In operation, the counter chain is actuated by a selected train of impulses derived from any suitable source such as a computer selecting gate. The counting chain is in the illustrated state at the beginning of a counting sequence due to the forced positive excursion of the clearing line :323. The arriving negative-going impulse passes through the short time constant circuit M9, 42| and diminishes or cuts off the iiow of current through the resistor M8 in the cathode circuit of the input valve M6, permitting the cathode end of this resistor to become more negative, which potential shift is transmitted through the diode 0| 2 to the anode 406, where it initiates the changeover process transferring conduction from the left-hand side to the right-hand side of the flip-flop 390. This develops a negativegoing impulse delivered to the input of the stage [i215 to initiate therein the same sequence of events which in turn triggers oif nip-flops 025, 026, 027, and 020. successively arriving impulses cause continued operation of the counting chain in a manner familiar to those skilled in the art. The standby state corresponds to a number expressed in binary notation as 111111, or, decimally, 63, and in this state the horizontal line 060 in the function table is maintained at ground potential or a few volts positive with respect thereto. For the next 28 counts no output line from the function table is energized, whereby all remain at a potential of about minus 17 volts with respect to ground. 0n the twenty-ninth count, the combination 011101 (equals 29) is set up in the register and the line 06| swings positively to ground potential or slightly above. The next count sets up the combination 011110=30 and makes the line 052 positive with respect to ground, while the next count sets up the combination 011111=31 and changes the potential of the horizontal conductor 563 to one slightly positive with respect to ground. These are employed in conjunction with the outputs of the previously described registers to select individual control The valve i l2 lines to perform the various sequences required in the execution of desired switching operations.

Thereafter, a negative-going impulse is applied to the capacitor 499 to charge the capacitor @58 through the diode in the valve 005 and bias the control grid 50| in valve 495 to cutoff, making the potential of the anode 502 and the control grid 501i of the valve 501 connected therewith more positive. This develops a positive-going impulse acrossV the cathode resistor 505 associated with the valve 50'! which is impressed on the anode of the diode i522 and its counterparts in the other nip-flops to cause the left-hand side of the flip-flops 399 and |24 through 20 to become conductive.

The auxiliary decoding function tables which have been described in connection with Figures 1, 3 and 4 may be connected with a main decoding function table such as that shown in Figure 5, where the function table of Figure 1 is presented at the upper left-hand corner, the function table of Figure 3 appears centrally in the bottom portion of the drawing and the function table of Figure 4 is repeated at the upper righthand portion of the drawing. Identity of reference characters has been observed throughout in this drawing. The output conductors of the decoding function table of Figure 5 are numbered 550 through 522 and are designated as well by letter abbreviations for the function to which they correspond. These lines are individually returned through resistors 525 through 6?, respectively, to positive supply lines of the potential indicated. Diodes connect the various input lines with the main decoding function table output lines GGD-622 at the points indicated. It may here be noted that the output lines of the associated function tables are directly connected with the input to the main decoding function table, and, hence, also represent input lines for main table as well as output lines for the auxiliary tables. This is in contrast with the arrangement of Figure 2 which interposed buffer valves between the output lines of the auxiliary function tables and the input lines to the main decoding function table.

It will further be noted that the supply potentials to which the main decoding function table output lines are connected vary over the range plus 60 to plus 160 volts. The magnitude of the resistors 625 through 6ft? also varies somewhat, though not over the samel range. For example,'the resistors 525, 82E, 627i, 629, 535, 530, G3i, 530, 6F50, 502, 654, 645, 6&6, and Sii? may have a magnitude of 15,000 ohms, while the resistor 628 may have a value of 12,500 ohms; 530, 533, 634|, 54|, and 543, may have a value of 12,000 ohms, and the resistors 63|, 532, and 03S may have a value of 10,000 ohms.

The signicance of the different voltages and resistances becomes fully apparent only when Figure 5 is studied in conjunction with the following Figure 6. n anticipation of the presentation of that ligure it may be remarked that the differing voltages and resistances are proportioned in accordance with the expected load presented by the apparatus in Figure 6 in the form of diode back resistances and other currentconsuming elements.

No attempt will be made to describe each of the output possibilities, it being felt that the development of these possibilities for one or tivo cases should establish the rule for further independent investigation thereof.

positive excursion, the line 600 also becomes positive, the balance of the lines remaining at about minus i7 volts with respect to ground. This corresponds to conduction in the valves 63 and 85 of Figure l and of the valves 32E, 323, and 324 in -Figure 3. The excitation of the line 50! is independent of the conductivity pattern in the apparatus of Figure Il. If now the lines I and 333 become positive, the selected line will be 602 or 66, depending upon the conduction pattern withi. the apparatus of Figure 4. Since the apparatus of Figure 4 is performing a counting operation the line 692 will first be energized, followed by energization of the lines bild. During this cycling operation, the rest oi the output lines from the decoding function table of Figure 5 remain at approximately minus 17 volts with respect to ground.

The various combinations possible in the apparatus already described have now been resolved into the selective excitation of one of a large number of conductors. As a result of this selective excitation, it is now desired to energize a controlled pattern of many conductors, and the nework so far described is therefore connected with the apparatus of Figure 6 whose horizontal conductors represent input conductors and are identiiied by the reference characters appearing in Figure 5. rlhis one-to-many, or encoding, function table has lines Si and illl through 622 inclusive as its output conductors. The output voltages are developed across individual members of a bank of resistors lili] having one end returned to the negative supply bus i l. The lines 655 and S55 are connected to the anodes of a pair of diodes 58'! and 686 whose cathodes are connected together and to one of the output resistors. Similarly, the output lines Bilt, 563, and Gti are connected with the anodes of diodes Elie, E96, and @Si whose cathodes are joined together to a single output resistor. The lines i512, 613, and till are similarly connected through diodes 692, 593, and B94, the lines t'i'l and Sl being similarly tied through the diodes SSS and 596, and the lines 684, and 685 through the diodes 69'! and 698.

Since the resistor associated with the cathodes of such pairs of diodes experiences a positive potential when either of the function table output lines associated therewith becomes positive, these diode connections may be regarded as butler connections. For example, the positive excitation of the line tti! excites output conductors 555, Elli, and 85, making the associated output resistor terminal positive and impressing on the companion diodes 68S, 595, and 697 a reserve potential whereby the diode presents its reverse resistance, minimizing leakage current through the associated diode networks, which would tend to reduce the maximum output voltage available. In connection with the selection of loading resistors and voltages previously discussed, it may be noted that the line Soil has associated with it three diodes feeding branch circuits including eight diodes and is connected to the positive supply bus lzii through a 15,000 ohm resistor 525. On the other hand, the line .563 has associated therewith seven diodes feeding branch circuits having a total of nine diodes for which back ciurent is to be supplied. Because of the greater back current requirements, this line is returned to the positive supply bus Hill through a 12,500 ohm resistor. The loading on this line would be even heavier were it not for the interposition of the buier diodes B81, 689, and 690, replacing 14 the back resistance of three diodes with the back resistance of a single diode.

The function table selecting network described supplies a convenient and high speed means for translating multiple coded inputs into one or many arbitrarily coded outputs. Their utility is considerable and they may be employed in many environments with such modification as the circumstances indicate to be desirable. Heater and anode supply circuits for operating the electric valves shown herein have been omitted, as any of the well known configurations of this type may be used in the practice of the invention.

lt will be obvious to those skilled in the art that the invention may find wide application with appropriate modification to the individual design circumstances, but without substantial de parture from the essence of the invention.

What is claimed is:

l. In combination, and second potential clusters, an electric valve conr ected in series with a load impedance between s suppl conductors, a first unilateral conductor c ^iected in a iirst sense between the valve end of said t load impedance and a first reference potenconduetor, a second unilateral conductor o nected reverse sense between valve of first load impedance and a second reference potential conductor, a signal line, a second impedance connected between said signal line and a supply conductor, and a third unilateral conductor operatively connecting said signal line with the junction between said rst second unilateral conductors.

2. In combination, a plurality or" electric networks individually characterized by at least two mutually exclusive stable electric states, a source of reference signals placing each of said networks in one or" its stable states, a transmission line characterized by delay of the signals transmitted therealong, connections extending individually from spaced regions on said transmission line to selected ones of said electric networks whereby transmission line im ulses induce the other of said stable states therein, plurality of signal lines individually returned through bilateral impedances to reference potentials, a plurality of selecting lines adapted to vary in potential under the control of said electric networks, a rst set of unilateral conductors c necting selected members of said signal .li with selected members of said selecting lines unique combinations, a second set of unilateral conductors connecting in a first sense said lecting lines to iirst reference poten' ductors, and a third set of unilateral connecting in reverse sense said sele I to second reference potentional conductors.

3. n combination, a first selecting network having input and output conductors adapted to receive a plurality of stimuli over a corresponc ing plurality of input conductors and uniquely energize a single output conductor in to unique input combinations, a second network having input and output conci' adapted to receive a plurality of ove corresponding plurality of input conductors a uniquely energize a single output conductor response to unique input combinations, pedances individually connecting said put ccnductors to a source of electric energy, unilateral conductors connecting in a first sense said input conductors to rst reference pote'. conductors, second unilateral conductors with impedances connecting in reverse sense said input conductors to second reference potential conductors, a third selecting network comprising the output conductors oi said rst and second networks as input elements andhaving a plurality of output conductors separately and individually excited in response to unique input combinations, and a iourth selecting network comprising the output conductors of said third selecting network as input conductors and having a plurality of output conductors excited in unique combinations in response to the excitation of individual input conductors.

4. In combination, a first selecting network comprising a plurality oi input conductors connected with corresponding electric valves a plurality of outputiconductors separately and individually excited in response to unique input combinations, impedances individually connecting said input conductors with a source of electric energy, a second selecting network comprising a plurality of input conductors connected with a second set of corresponding electric valves and a plurality of output conductors separately and individually excited in response to unique input combinations, impedances individually connecting said second input conductors with a source of electric energy first unilateral conductors connecting in a rst sense said input conductors to rst reference potential conductors, second unilateral conductors connecting in reverse sense said input conductors to second reference potential conductors, a third selecting network comprising the output conductors of said rst and second networks as input elements and having a plurality of output conductors separately and individually excited in response to unique input combinations, a fourth selecting network comprising the output conductors of said third selecting network as input conductors and having a plurality of output conductors excited in unique combinations in response to the excitation of individual input conductors and impedances individually connecting the output conductors of said third network with voltage levels varying systematically with variation in the number of fourth network output conductors excited by said third network output conductors.

5. fn selective signaling apparatus, a plurality of input conductors, a plurality of intermediate conductors, a rst group of unilateral conductors connected in a first sense between a rst group of said input conductors and a i'irst group of said intermediate conductors, a second group of unilateral conductors connected in said rst sense between a second group of said input conductors and a second group of said intermediate conductors, an output conductor, unilateral conductors connected in said first sense between said intermediate conductors andl said output conductor, and electronic switching means respec tively connected to said input conductors, said intermediate conductors and said output conn ductors for selective actuation thereof.

6. In combination, iirst and second pairs of alternatively conducting electric valves, conducting members individually connected with said valves, means to apply operating potentials through said conducting members to said valves, a first reference potential conductor connected through a unilateral conductor in a first sense to each oi said conducting members, a second reference potential conductor connected through a unilateral conductor in reverse sense to each of said conducting members, an Output set of four conducting members, a

rst group of unilateral conductors connecting the first and secondv of said output conduc members withone of the members oi said first valve, pair, Va second group of unilateral conductors connecting the third and fourth ci said output conductors with the other of the members of said rst valve pair, a third group of unilateral conductors connecting the first and third oi said output conductors with one or the members oi" said second valve pair, and a fourth group oi" unilateral conductors connecting the second and fourth oi said output conductors with the other of the members orl said second valve pair.

7. In combination, a first plurality of conduct ing membersdndividuaily connected with electric valves, resistances ci predetermined magnitude individually connected between elec ric points and said iirst conducting merope-rs, i" 'st and second reference potential conductors,A unilateral conductors connecting-in a first sa d s..

conducting members to said first reierence p tential conductors, unilateral conductors con-- necting in reverse sense said conducting niemeis to said second reference potential conductors, a second plurality of conducting members, unilateral conductors linking selected ones or". -irst plurality of conducting members with lected ones of said second plurality of conducting members, and resistances having a magnitude not greater than one-nith the magnitude of said st resistances individually connecting the con-ductors oi said second group with electric supply points.

8. in combination, a irst set of input eonductors, a iirst set of output conductors, unilateral conductors interconnecting selected members of said iirst set of input conductors and selected members o said iirst set of output conductors, a second set oi input conductors, a second of output conductors, unilateral conductors interconnecting selected Vmembers of said second set of input conductors and selected members or said second set of output conductors, first and second reference potential conductors, unilateral conductors connecting in a first sense said input conductors to said first reference potential con-- ductors, unilateral conductors connecting in reverse sense said' input conductors to said second reference potential conductors, a third set of output conductors, unilateral conductors linking selected members of said rst and second sets of output conductors with selected members oi said third set of output conductors, resistances connecting individual ones or" said third set of output conductors with` electric supply points, a fourth set of output conductors, and unilateral conductors connecting selected members or said third set of output conductors with selected members of said fourth set of output conductors.

9. In combination a plurality oi conductor pairs, a like plurality o electronic switching means, means to apply an operating potential to the output of the corresponding switching means, means to apply high-frequency actuating signals to the input of each oi said switching means to symmetrically excite each conductor pair, an additional plurality of individual conductors, a first array or" .unilateral conductors connected between selected members of said pairs and said individual conductors in a given sense, a second array of Vunilateral conductors connected between different selected members of said pairs and said individual conductors, a third array oi unilateral conductors connecting in a first sense each member of said conductor pairs to a iirst 17 reference potential conductor, and a fourth array of unilateral conductors connecting in reverse sense each member of said conductor pairs to a second `reference potential conductor.

10. First and second potential supply conductors, a plurality of pairs of electric Valves, each member of said pairs being alternately conductive and "connected in series with an impedance between said supply conductors, a plurality of signal lines individually returned through associated impedances to third supply conductors, a rst setfk of unilateral conductors interposed between eah member of said pairs of electric valves and selected ones of said signal lines in individual unique combinations, first and second referencey` potential conductors, a second set of unilateral conductors connecting in a first sense the members of said pairs of electric valves to said r'stfreference potential conductors, and a third set of unilateral conductors connecting in reversesense the members of said pairs of electric valves to said second reference potential conductors.

11. In combination, a plurality of input con ductors, a plurality of output conductors, unilateral conductors connecting individual ones of said input conductors with variably sized groups of said output conductors, energizable exciting circuits connected with said input conductors, rst unilateral conductors connecting in a first sense members of said energizable exciting circuits to rst reference potential supply conductors, second unilateral conductors connecting in reverse sense said members to second reference potential supply conductors, means to apply an operating potential to said members, means connected with said energizable exciting circuits to effect selective energization thereof, and impedances connected between said input conductors and electric potentials, the magnitude of said potentials and said impedances being selected to develop substantially equal voltages at said input conductors.

12. The combination according to claim 11 in which the voltage levels of said potentials vary systematically with the number of unilateral conductors connected to the associated input conductors.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,331,151 Hopkins Feb. 17, 1920 2,403,561 Smith July 9, 1946 2,428,811 Rajchman Oct. 14, 1947 OTHER REFERENCES Proceedings of the I. R. E., February, 1949, pages 139-147. 

